Glass containers may be coated for a variety of different purposes, including damage prevention, e.g., scratch and abrasion resistance, and strength retention. Such coatings may be applied to the glass containers at various points in the manufacturing process. For example, glass containers are conventionally coated with metal oxides, e.g., oxides of tin, titanium, vanadium, or zirconium at the “hot end” of the annealing lehr, and then overcoated with protective organic coatings at the “cold end” of the annealing lehr. Accordingly, these conventional coatings may be referred to as cold end or hot end coatings. U.S. patents that illustrate coating processes of this type include U.S. Pat. Nos. 3,323,889; 3,407,085; 3,414,429; 3,418,154; 3,425,859; 3,445,269; 3,498,825; 3,554,787; and 3,598,632.
A general object of the present disclosure, in accordance with one aspect of the disclosure, is to provide a process for coating glass containers that can improve certain desirable surface characteristics of the glass containers.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A process for forming an inorganic silica coating on a glass container in accordance with one aspect of the disclosure includes: (a) applying a sol-gel solution including a polysilazane and an organic solvent to an exterior surface of a glass container to form a sol-gel coating thereon, and (b) heating the glass container and the sol-gel coating in a water vapor-containing environment having a temperature between 150 degrees Celsius and 600 degrees Celsius to form an inorganic silica coating on the exterior surface of the glass container, wherein the silica coating has a hardness greater than 8.5 GPa and is bonded to the exterior surface of the glass container through a plurality of siloxane bonds.
In accordance with another aspect of the disclosure, there is provided a process for manufacturing a glass container having improved surface characteristics that includes: (a) forming a glass container, (b) applying a sol-gel solution including a polysilazane and an organic solvent to an exterior surface of the glass container to form a sol-gel coating thereon, and (c) heating the glass container and the sol-gel coating in a water vapor-containing environment having a temperature between 150 degrees Celsius and 600 degrees Celsius to form an inorganic silica coating on the exterior surface of the glass container, the silica coating having a hardness greater than 8.5 GPa and being bonded to the exterior surface of the glass container through siloxane bonds.
In accordance with yet another aspect of the disclosure, there is provided a glass container having improved surface characteristics that includes: a glass substrate that defines the shape of the container and provides the container with a closed base at an axial end of the container, a body extending axially from the base and being circumferentially closed, and an open mouth at another axial end of the glass container opposite the base; and an inorganic nonporous silica coating formed on an exterior surface of the glass substrate. The silica coating has a hardness greater than 8.5 GPa and is bonded to the exterior surface of the glass container through a plurality of siloxane bonds.